Abstract
Anodic coatings were formed on aluminum in 10wt% chromic acid solution by pulse current with a negative component to examine the effects of anodizing voltage, temperature and negative current density.
It was found that thick coatings cannot be obtained when negative current is high, can when negative current controlled. The coating grows at the highest when the negative component is held to 11%. The cells of coatings formed by pulse current with a negative component were of more uniform size, pores were branching, and larger in size than with DC coatings. Many pores were observed in the barrier layer of anodic coatings formed by pulse current.
